Bob, 

Thanks for your response. The machines I'm using are a 
Soltec Sigma and Soltec Galaxy, both with nitrogen. ( have 
ruled out nitrogen as a cause)
I have lowered the setings on the main, chip, and 
smartwave (Sigma has only a main and chipwave) to the point 
where I am barely soldering the bottom of the board. This 
creates insufficient solders, misses, and shorts. 

I am beginning to get the feeling that this condition 
is inevitable when using these devices on the bottom of the 
board. Maybe others have this problem and are not aware of 
it because they dont x-ray, or have the problem but wont 
admit it. I have gotten very few responses to this subject.

I have tried the glass plate approach, but will give it 
another try.

I would appreciate any other suggestions you may have. My 
current
plan is to design some fixtures that would put the boards at 
a 45 degree angle and also a 20 degree angle to the wave.

Again, any other input you may have will be appreciated, as 
this problem has consumed my time for the last 5 weeks. 


Thanks,

Al Boulais

ps: if I ever solve this I'll let you know the solution



______________________________ Reply Separator _________________________________
Subject: Solder Under IC's
Author:  [log in to unmask] at !INTERNET
Date:    9/8/95 8:07 PM


The problem is seen on Electrovert Omega waves and Soltect SMART waves you need 
to turn down the setting to reduce the insidence of the problem. Stick parts to 
a lev check to evaluate the best settings.

Bob Willis UK
Tel 01245 351502
Fax 01245 496123